FR2782932A1 - Device for purification in forced vacuum of simple and composite materials comprises transparent quartz receiver for substance to be purified - Google Patents

Abstract

The substance to be purified is placed in a receiver (1) of transparent quartz with one end closed and the other having a neck (2) in which a transparent quartz escape tube (3) is introduced. This penetrates into the receiver over five to nine tenths of its length and extends inside the receiver for sufficient length to bring the vapor to a condensation zone The device can convert solids or liquids to vapors at a pressure between 0.1 and 20 torr and temperatures not exceeding 1100 deg C. To increase the time for which the vapor is confined in the receiver, the end of the tube is partially obstructed. The device contains a condensation zone where the purified substance is deposited. A collection tube for the condensed vapor in the form of a boat is placed in the lower part of the condensation zone, with its upper part open. The device is arranged horizontally or vertically, and if vertically then the vapor condenses on a support which conducts heat well. An Independent claim is also included for a purification process using the above apparatus, comprising mixing the substance to be purified with a small quantity of the same substance purified and slightly oxidized, to encourage the oxidation of non-volatile impurities accumulating in the receiver. To increase the productivity of the purifier, the receiver contains several vapor escape tubes which are collected in a second receiver from which the material is directed to the condensation zone via an escape tube.

Description

The present invention relates to an apparatus for purification

  of simple bodies and compounds capable of passing from solid or liquid state to vapor state and having a vapor pressure of between 0.1 and 20 torr at temperatures not exceeding 1100 C. The only limitation imposing this The temperature limit is the use of quartz for the construction of the apparatus according to the invention (which implies that only substances which do not react with quartz can be treated there). The device whose

  Description is given below was developed to improve the implementation of the purification process described in our international patent application filed July 02, 1996 under N PCT / RU 96/00176 [1]. This process was designed to ensure elimination

  residual impurities as extensive as is required by semiconductor physics so that the materials in question can be used for the manufacture of electronic devices. Indeed, one of the major objectives of research in the fields of optronics and special sensors is the development of production technologies for compounds of the general formulas A2B6, A4B6 and some others. Since all of these compounds are vaporized (sublimate) at temperatures well below their melting points, the zone melting process can not be applied to them, which, together with appropriate chemical treatments, can reduce content of the residual impurities below the analytical detection thresholds of the impurities. Of course, the apparatus according to the invention can be used for the deep purification of all other inorganic elements and compounds by replacing, if necessary, quartz with any other material for the construction of the apparatus. Sublimation purification processes (solid -> vapor ---> solid) and vaporization (liquid -> vapor -> liquid or solid) are known and widely used for a long time [2]. The material to be purified contained in a flared crucible is placed in a vacuum chamber where a high vacuum (10-7-10-9 torr) must prevail. The temperature of the charge is raised until the pressure of the steam produced reaches 10-3-10-2 Torr. At these pressures, the free-flow length of the particles is comparable to the distance between the vapor source and the surface on which the atoms and molecules emitted by the charge condense. Between these two surfaces must exist a temperature gradient (T condensation <T vaporization). The impurities contained in the substance to be purified can be classified in three groups: impurities known as easily vaporizable; impurities with difficult vaporization and impurities having vapor tensions comparable to that of the purified substance. Considering only that part of the flow of vapor that falls on the condensing surface, the purification effect would concern, as a first approximation, only the

  less volatile impurities that accumulate in the load throughout the process. The volatile impurities mixed with the molecules of the purified substance A2 designating cadmium or zinc, A4 tin and lead, B6 sulfur, selenium or tellurium.

  reach the condensation surface. As the condensation process is generally fast enough, some of the volatile impurities are captured by the condensate, while the others are re-evaporated and will settle on the cold walls of the vacuum chamber. It all depends on the experimental conditions, the condensation coefficients of the impurities and the impurity content of the feed. Impurities whose vapor pressures and condensation coefficients are not very different from those of the purified substance are not eliminated. In sum, the effectiveness of these purification processes depends not only on the physico-chemical properties of the purified substance and those incorporated impurities, but also conditions of transport of the vapor from the source to the condensation surface. In order to further reduce the content of impurities, it is necessary to repeat the

  process using each time the deposit formed on the condensation surface as a source. It follows that the quantity of purified substance decreases more and more. The disadvantage of this purification process is that it is not cyclic and that its yield of purified material is low.

  A cyclic sublimation purification process was developed by one of the authors [3]. In this last process we submit to a succession of acts of sublimation-

  condensation of small portions of an initial charge maintained at a temperature lower than that of an effective sublimation, this succession of sublimation-condensation acts was ensured by the displacement of a constant temperature gradient along a chamber to void of annular form. Although incomparably more efficient than the process of the repetition of the processes carried out in a vacuum chamber, this process does not make it possible to eliminate impurities whose compounds would have thermal variations in pressure that are not very different from those of the purified substance. In order to overcome the shortcomings of these processes, which did not make it possible to obtain semiconductor materials of the required purity, we were led to develop the new method of vapor phase purification described in [1]. Substantial semiconductors are used as the substance model to be purified, and the results of quantitative analyzes of impurities (spectrochemical and mass spectrometric analysis) can be supplemented by the study of the physical properties of semiconductors (for example, photo- and cathodoluminescence spectra) which are hypersensitive to the presence of impurities. The apparatus forming the subject of the present invention was designed to implement the essential principle of the purification method described by the authors in their international patent application filed on July 2, 1996 [1]. It is therefore of the same type as the one illustrating the latter. Unlike known methods of sublimation purification, in this process the vapor formed during the heating of the substance to be purified is confined for a finite time in a transparent quartz tubular container containing said substance. This container is closed at one end, and at the other end, it is shaped in the form of a neck through which the substance to be purified is introduced. This container is placed at the bottom of a vacuum chamber constituted by a transparent quartz tube closed at one end, the other end being connected to a vacuum pump. The whole is surrounded by an electric resistance furnace that raises the temperature of the substance until the pressure of its vapor 5 becomes equal to a few tenths or tens of torr. Steam escaping through the neck of the vessel passes through several concentric quartz tube systems or

  eccentric, then arrives in the condensing zone of the vapor, where the purified product is deposited. The confinement of the steam in the purification vessel promotes the formation of stable molecules from the impurities with or without participation of the constituents of the purified substance, in particular metal oxides and chlorides, whose vapor pressures at the temperatures used are substantially smaller than that of the purified compound.

  In other words, volatile impurities are converted into low volatility compounds. While recognizing the eminent role played by the most exothermic reactions between impurities leading to the formation of stable molecules, not very volatile; the emphasis was placed in [1] on the formation of impurity deposits on the solid surfaces along which the steam was flowing after being discharged from the container. In fact, solid deposits had been observed on these surfaces and it was deduced that in the case of a flow of vapor in a laminar regime, the impurities were expelled from the flow of vapor in the viscous layer adhering to these solid walls. Later, we found that the purification effect was mainly (or exclusively) determined by the chemical reactions occurring in the vessel, the probability of obtaining the most stable molecules being proportional to the frequency of the shocks between the different atoms. and vapor phase molecules, thus the pressure and the retention time of the vapor in the container. In fact, the authors of the present invention regularly observe in the purification experiments of elements and sublimable compounds that after these experiments, involving hundreds of grams of substance,

  contained in the container, ponderable quantities of solid residues, in which the spectrochemical analysis made it possible to identify oxides, chlorides and sulphides. In the majority of cases, these solid residues mainly contained stable oxides at low vapor pressure. The oxygen necessary for the formation of these oxides comes, on the one hand, from the oxygen absorbed on the inner surfaces of the apparatus, on the surface of the substances.

  purified oxygen, and secondly, dissolved and incorporated oxygen in these substances, which generally represents a total of nearly 1019 oxygen atoms per cubic centimeter of substance. When the mass of the substance subjected to purification in the apparatus of the present invention was greater than one kilogram, a few percent by weight of the same substance (or

  analogous substance) previously purified and weakly oxidized to increase the amount of oxygen in the purification vessel.

  On the other hand, as the confinement time of the vapor in the vessel increased, the solid deposits on the solid surfaces out of the container became less and less detectable. In order to increase the retention time of the steam in the container, a quartz exhaust tube penetrating deep into the container and extending well beyond the edge of the neck was successively introduced into the neck. In order not to increase too strongly the laminar flow resistance of the steam in this tube,

  could not decrease its diameter below about 10 mm. Also, to enhance the containment of steam in the vessel, the present inventors have partially closed the opening of the exhaust tube by welding at its inner end a quartz plate pierced with a smaller diameter orifice than that of the tube or a tip shaped truncated cone.

  Whereas in [1] only the horizontal arrangement of the apparatus, corresponding to the purification process forming the subject of said invention, has been envisaged in the case of the apparatus forming the subject of the present invention, o solid honeycombs-type surface systems have been removed, on which solid impurity deposits would be formed, it is possible to envisage both a horizontal arrangement and a vertical arrangement of the purification apparatus. FIG. 1 is a horizontal section, and in FIG.

  2, the vertical arrangement of the device.

  The apparatus according to the invention consists of the following elements.

  1. A transparent quartz tubular container (1) 50 to 200 mm in diameter and several tens of centimeters in length, hermetically sealed at one end, the other end

  having been curved and perforated with one or more orifices, generally of circular shape, provided with collars (2) with a diameter of between 10 and 40 mm, distributed more or less arbitrarily on this curved surface. In the simple case of a single orifice, it will be placed at the center of the curved surface.

  2. In these orifices are housed one or more tubes (3) in transparent quartz, having diameters slightly smaller than the diameters of the collars, in order to be put in place or removed without difficulty. These tubes, called purified steam exhaust tubes, penetrate deeply into the tubular container until the end of these tubes is about ten centimeters from the closed end of the container (1). It is not necessary, in the case of several exhaust tubes, that they are all driven to the same

  depth. The opening (4) of this or these exhaust tubes is partially closed to reduce the rate of escape of the steam. As indicated above, a low vapor flux implies a greater probability of formation of stable oxide, sulphide or chloride molecules, hence a deeper purification of the treated substance.

  The opening opening of the exhaust tubes is thus reduced to 4-10 mm. In the case of a single exhaust pipe (Figure 1), the latter extends out of the purification vessel over a length of several tens of centimeters. When there are several exhaust tubes, they end up in a second tubular container (5) through holes duly bonded and arranged perfectly symmetrical with respect to the openings of the first container (Figure 3, a and b). This second container is generally shorter than the first, the ends of the exhaust tubes penetrating almost on the convex wall 5 front of the container. Through the front wall, generally in the center of the latter, the exhaust tube (6) (FIG. 3, a) is passed through the vapor collected in this second container (5). This last steam exhaust tube extends out of the container (fig.3 a) over a length of one or several tens of centimeters. The tubular steam purification and collection containers as well as the exhaust tubes are arranged in a vacuum chamber (7) consisting of a transparent quartz tube hermetically closed at one end, the other end being connected to a pump empty providing a vacuum of at least 10-5 torr. The vacuum chamber is placed in an electric furnace comprising two independent heating coils (8) and (9). The main winding (8) extends from the closed end of the vacuum chamber to about ten centimeters beyond the end of the extreme exhaust tube, pointing to the condensing zone. The second winding (9), adjacent to the main winding, makes it possible to set the temperature of

  condensation of the vapor of the purified substance. The main winding to reach any temperature up to 1100 C serves to heat the purified substance until its vapor pressure corresponds to a laminar flow regime, that is to say a few tenths to dozens of torrs.

  The condensation zone (10) is constituted according to the nature of the purified substance and the nature of the treatments to which it will be subjected later, either by a condensation surface (generally concave) associated with a quartz cylinder or by a solid body conductive the heat (eg graphite) (11), Fig. 2, extending out of the region heated by the second winding of the furnace, or by a partially closed tube at both ends and forming nacelle (14) for subsequent melting the deposit resulting from the

  condensation of the steam, or by a tube open at both ends (12), of sufficient length so that the steam leaving the exhaust tube can condense at least 90% on its inner wall (FIG. (13) The mass of the deposition of the purified substance is generally 80-85% of the initial charge, about 10% of this mixed with the solid residues is left in the purification vessel.

EMBODIMENTS OF THE INVENTION

  1. Purification of zinc telluride (ZnTe).

  Zinc telluride is a semiconductor with a bandwidth of 2.3 ev (at 300 K) and could therefore be used for the manufacture of lasers emitting a green light (5255 nm). The compound was obtained by direct synthesis of the constituents previously purified using the apparatus according to the invention. Synthesis processes, involving weighing, transfers, etc. accompanied by a significant pollution of the constituents (in particular, by the oxygen of the air). The synthesized compound (700 gr) was introduced into a purification vessel 80 mm in diameter and 600 mm in length (Fig. 1) and placed near the neck. An exhaust tube 30 mm in diameter and 800 mm long is introduced into the neck; the opening of the tube, located near the bottom of the purification vessel, was closed by a circular quartz glass pierced with an 8 mm opening (4). This assembly was placed at the bottom of the transparent quartz vacuum chamber (7), the other end of which was connected to a turbomolecular pump. The vacuum chamber was placed in a resistance furnace with two independent windings. The winding (8), corresponding to

  heating the purification container and the exhaust tube, the door to a uniform temperature of 880 C (+ 2). At a distance of 100 to 150 mm from the end of the exhaust tube, a temperature of about 700 to 500 ° C. is established by means of the second winding (9), thus ensuring the condensation of purified steam.

  The duration of the purification process was 45 hours, the amount of the purified compound which condensed on the walls of the collection tube in the form of a deposit (13) of 1 to 6 mm thick was found to be equal at around 420 gr. The mass of a deposit of smaller thickness was evaluated at about 70 gr. About 70 grams of compound were left in the purification vessel to avoid the vaporization of some impurities that concentrate in the vessel throughout the process. We can therefore count on a yield of purified product of the order of 80%. The results of mass spectrometer analysis of the impurities in several samples of the purified compound are given in Table 1. The differences between the results obtained on 4 samples are not very noticeable. The detection of photoluminescence spectra at 4K at different points of the maximum thickness deposition (see Fig. 4) confirms the purity of the zinc telluride obtained. In fig. 5, the cathodoluminescence spectrum recorded at 80K was reproduced. Note that when, even keeping the partial shutter glass of the opening of the exhaust tube, the temperature of the purification vessel (Tsub-950 C) was raised, the same amount of product had condensed into a shorter time (about 30 hours). The mass spectrometry data were about the same (overall purity of

  99.9996 in the first case and 99.9994 in the second).

  Table 1 (1 ppmn = 0.0001%) Element Ppm mass Element Plpm mass Element Ppm mass H ND Zn CONSTIUUANT Pr <0.02 Li 0.1 Ga <0.03 Nd - <0.06 Be <0.001 Ge <0.04 Sm <0.05 B <0.0006 As < 0.01 Eu <0.05 C 0.2 Se 0.8 Gd <0.06 N ND Br <0.03 Tb <0.02 O <0.3 Rb <0.02 Dy <0.05 F 0.02 Sr <0.01 Ho <0.02 Na <0.01 Y <0.02 Er <0.06 Mg 0.006 Zr <0.02 Tm <0.03 A1 0.005 Nb <0.2 Yb <0.06 If 0.005 Mo <0.04 Lu <0. 03 P <0.02 Ru <0.03 Hf <0.04 S 7 Rh <0.01 Ta ND Cl <0.02 Pd <0.04 W <0.07 K <0.02 Ag <0.01 Re <0.05 Ca 0.03 Cd <0.08 Bone <0.08 Sc <0.009 In <0.04 Ir <0.04 Ti <0.02 Sn <0.04 Pt <0.08 V <0.01 Sb <0. 02 Au <0.03 Cr <0.008 tHe coNsTm-uD Hg <0.09 Mn <0.004 I <0.02 TI <0.05 Fe <0.001 Cs <0.02 Pb <0.09 Co <0.008 Ba <0.03 Bi <0.07 Ni <0.001 The <0.02 Th <0.05 Cu <0.1 Ce <0.02 U <0.05

2. Purification of cadmium.

  Cadmium was subjected to purification in a horizontal purification apparatus

(Fig. 6).

  Since the solid cadmium vapor pressure near its melting point is less than 0.1 torr, a liquid cadmium bath maintained at 350 ° C (+ 2) was purified. As a result, a purification vessel of 100 mm in length, an exhaust tube (partially closed) 30 mm in diameter and 750 mm long was used. The end of the tube leaving the purification vessel penetrates a length of a few centimeters in a quartz tube (14) arranged in the form of a nacelle in its lower part, and open in its upper part (Fig.6). This condensation tube of the steam must be of sufficient length so that almost all the steam of the purified element condenses there (at about 200) by letting escape the volatile impurities. The mass of cadmium subjected to the purification was about 800 g. The duration of the purification process was 40 hours; having reduced the temperature created by the main winding (8) and raised the temperature in the condensation zone to 330 C, the deposit formed in the nacelle tube was melted and the current was cut off . The ingot (15) which was removed from the nacelle was formed of monocrystalline large grains of 5 to 12 mm. The ingot was easily detached from the basket. Its mass was equal to 520 gr. In the purification vessel (which had been previously covered with a carbon layer) about 160 grams of polluted metal and impurities were recovered. Spectrochemical analysis of the purified metal provided the following results: Table 2 Cu <2.10-6 Ag <2.10-5 Mo <6.10-5 If <6.10- 'Mg <6.10-6

AI <6.10-5

Bi <6.10-6 Ni <6.10-6 Co <6.10-5

Cr <6.10-

Pb <6.10-5

Sn <2.10-

Mn <6.10-6 Ge <2.10-5 Fe <2.10-5

Sb <6.10-

Hg <2.106 Zn 2.10-4 Na 5.10-6

K 6.10-6

Ca <2.10-5

3. Purification of tellurium.

  As at the melting temperature (452 ° C.) tellurium only has a vapor pressure of 0.2 torr, its purification was carried out at 520 ° C. in the liquid state. So we used

  the apparatus shown fig.4. The quantity of tellurium subjected to purification was 800 gr; it was purified previously purified tellurium having a purity of about 99.98%.

  After a 40-hour purification, the nacelle condensation tube (14) being at 300 ° C., the temperature of the active part of the apparatus was lowered to 300 ° C. and the temperature in the condensation up to 460 C, in order to melt the tellurium deposit and obtain an ingot. The ingot was easily detached from the quartz nacelle and was

  well crystallized. Its mass was found to be equal to 685 gr. Nearly 100 gr of polluted tellurium remained in the purification vessel.

  The purity of the tellurium obtained is recorded in Table 3.

  Table 3 (1 ppm = 0.0001%) Element ppm Element ppm Element ppm H ND Fe <0.007 Sn <0.04 Li <0.002 Co <0.006 Sb <0.02 Be <0.0003 Ni <0.006 Te MATRIX B <0.0004 Cu ND I <0.03 C 2 Zn <0.06 Cs <0. 009 N ND Ga <0.04 Ba <0.04 O 5 Ge <0.01 Hf <0.02 F <0.01 As <0. 03 Ta NA Na <0.01 Se 4 W <0.03 Mg 0.03 Br <0.01 Re <0.05 AI 0.05 Rb <0.05 Bone <0.08 If 0.01 Sr <0.05 Ir <0.03 P <0.04 Y <0.01 Pt <0. 08 S <0.1 Zr <0.01 Au <0.07 Cl 0.1 Nb <0.02 Hg <0.06 K 0.2 Mo <0. 02 Tl <0.06 Ca <0.1 Ru <0.01 Pb <0.05 Sc <0.003 Rh <0.008 Bi <0.02 Ti <0. 003 Pd <0.02 Th <0.02 V <0.003 Ag <0.02 U <0.02 Cr <0.004 Cd <0.2 Mn <0. 003 In <0.009

  4. Purification of cadmium telluride.

  Cadmium telluride was obtained by direct synthesis of purified cadmium and tellurium as indicated above. The mass of the polycrystalline ingot of cadmium telluride synthesized was 700 gr. The vertical variant of the purification apparatus shown in FIG. 2 was used. The purification vessel with a diameter of 70 mm and 500 mm in length was suspended in the vacuum chamber using studs welded to the surface of its upper part and which rested on supports welded to the internal surface of the vacuum chamber (not shown in Fig. 2). The 25 mm diameter and 650 mm long (partially closed) exhaust tube was also provided with tenons that held it in place in the neck. In order to promote the formation of low-volatility oxides and to accelerate the purification, nearly 5 grams of cadmium telluride, previously purified and then partially oxidized, were added to the cadmium telluride charge. The steam exiting the exhaust tube was condensed on a graphite cylinder (11) disposed in the condensing zone (10), its lower part exceeding the limit of the second winding (9) of the furnace, thus ensuring good evacuation of heat and establishment of a suitable temperature gradient. The condensation temperature of the steam was between 610 and 625 C. The cadmium telluride was maintained throughout the purification period at 770 C. The duration of the purification process was 30 hours. By condensation on the graphite support (1 1), a polycrystalline ingot (13) (a ball) was obtained, having in its central region monocrystalline grains of several millimeters

  long. The weight of the ingot was found to be 600 grams. About 50 grams remained in the purification vessel. A thin deposit formed on the wall of the vacuum chamber in the condensation zone. The determination of the impurities was carried out using a mass spectrometer. The results are shown in Table 4.

  The 4 K photoluminescence spectra (Figure 7) at several points of the ingot revealed the existence of inhomogeneities whose existence can be attributed either to a

  local concentration of impurities, either structural defects still important in the polycrystalline ingots or both causes.

  1 Table 4 (1 ppm = 0.0001o%) Element ppm Element ppm Element ppm H ND Zn 0.08 Pr <0.1 Li <0.001 Ga <0.02 Nd <0.4 Be <0.003 Ge <0.02 Sm <0.6 B 0.005 As 0.02 Eu <0.4 C ND Se 10 Gd <0.5 N ND Br <0.03 Tb <0.1 O 10 Rb <0.06 Dy <0.4 F 0.2 Sr <0.01 Ho <0.1 Na <0.01 Y <0.01 Er <0.4 Mg <0.6 Zr <0.03 Tm <0. 1 AI <0.2 Nb <0.07 Yb <0.4 If <0.5 Mo <0.08 Lu <0.3 P <0.5 Ru <0.08 Hf <0.4 S <0.04 Rh <0.03 Ta ND Cl 0.4 Pd <0. 08 W <0.5 K <0.03 Ag <0.04 Re <0.2 Ca <0.1 Cd CONSTLITUANTOs <0.8 Sc <0.003 In <0.09 Ir <0.3 Ti <0.002 Sn <0.1 Pt <0.5 V <0.02 Sb <0.08 Au <0.7 Cr 0.006 TcNsTruRAN-rHg <0.5 Mn ND I <0.05 TI <0.1 Fe ND Cs <0. 03 Pb <0.1 Co <0.02 Ba <0.2 Bi <0.08 Ni ND The <0.08 Th <0.2 Cu ND Ce <0.07 U <0.2 Examples of device implementation according to the invention are not limiting nor qualitatively, in that the apparatus can be made not only of quartz but also

  in any material suitable for the purification of very different sublimable substances, nor quantitatively in the sense that the dimensions of the apparatus and therefore the quantities of purified substances are in no way limited to the dimensions mentioned in the exemplary embodiments.

  The industrial applications of the apparatus cover the production of substances of very high purity, such as sublimable single bodies and semiconductor compounds of various general formulas, as well as other substances whose

  properties largely depend on their purity.

  The apparatus according to the invention makes it possible to obtain in a single operation and with a yield greater than 75% of purified material substances of purity 5 N and beyond.

  1. S.A. Medvedieff, Yu.V. Klevkov International patent application PCT / UK

96/00176 of 02 July 1996.

  2. Mullin "Crystallization", chap.8. 1972

  3. S. Medvedieff, US Patent No. 5,201,985 of April 13, 1993.

  4. L: Landau, I.Lifchitz Course of Theoretical Physics, volume "Mechanics of fluids". Translation. 1993

Claims (8)

  1. Apparatus for deep purification in high vacuum of simple and compound bodies, capable of passing from solid or liquid state to vapor state at a pressure of between 0.1 and 20 torr at temperatures not exceeding not 1 1 00 C, characterized in that the substance to be purified is placed in a transparent quartz purification vessel (1), one end of which is closed and the other end is provided with a neck (2) in which a transparent quartz tube, said exhaust tube (3), penetrating into the container five to nine tenths of the length of the latter and extending beyond the container for a length sufficient to bring the vapor to the condensation zone (10). 2. Apparatus according to claim 1, characterized in that to increase the confinement time of the steam in the purification vessel, the end is partially closed.   (4) the exhaust tube that is depressed.   3. Apparatus according to claims 1 and 2 having a condensing zone   (10) the deposit (13) of the purified substance is formed.   4. Apparatus according to claim 3, characterized in that there is arranged in the condensing zone (10) a condensed vapor collection tube arranged in the form of a nacelle   in its lower part and open in its upper part (14) .20 5. Apparatus according to any preceding claim characterized by a horizontal or vertical arrangement and that in the case of the vertical arrangement, the   Steam condenses on a good heat conductive carrier. 6. Purification process using the apparatus according to the claims above characterized in that it consists in mixing with the substance to be purified a small   quantity of this same substance, previously purified and slightly oxidized, to promote the formation of low volatility impurity oxides, accumulating in the container   of purification. 7. Apparatus for purifying single bodies and sublimable compounds at temperatures below 1100 C, according to any one of claims 1 to 5,   characterized in that to increase the productivity of the purification process, the purification vessel (1) is provided with a plurality of steam exhaust tubes (Fig. 3a, b) which is   first collected in a second container (5) where it is directed to the condensing zone (10) by means of the exhaust tube (6). 8. Application of the apparatus according to any one of claims 1 to 5 and 7 to   purification of semiconductor compounds.